Conventional powered brooms typically utilize an elongated cylindrical drum having a plurality of stiff bristles projecting radially outwardly from the periphery of the drum. The drum is normally rotated about its axis at high speed (e.g., 160 rpm) in a manner such that the bristles engage the surface to be cleaned as the drum is rotated. The bristles push the loose material (i.e., dirt and dust) forward and also lift the loose material upwardly by the action of the bristles being released from contact with the surface being cleaned. The resilient bristles inherently bend backwardly when contacting the loose materials and the surface being cleaned and then the bristles spring forwardly after the drum has rotated to a point where the bristles lose contact with the surface. When the bristles spring forwardly, they tend to flip or project particles of the loose material into the air and in a trajectory in front of the rotating drum of bristles.
The constant springing back and forth of the bristles causes problems. A dust or air pollution problem is created by the continual lifting and projection of the loose particles into the air. The air turbulence created by the high speed rotation of the drum with outwardly extending bristles further disburses the dust cloud around the broom and keeps the loose particles airborne during operation of the power broom. The cloud of dust and loose materials may create a potential health hazard. It is not unusual that operators of such power brooms must wear air-filtering breathing apparatus or that the powered broom device must have an enclosed operators cab. Furthermore, the forward trajectory of the loose particles, and the accompanying cloud, scatter dirt and loose materials to secondary areas which must then be cleaned. This is particularly inefficient in cleaning large areas, because the loose particles may project and settle onto areas which have previously been swept, requiring those areas to be cleaned again.
Dust suppression systems have been developed for use with conventional powered brooms. The typical dust suppression system sprays a fine mist of water into the cloud. Such dust suppression systems require a relatively large tank of water to be carried on the powered broom device. If the powered broom apparatus is of an insufficient size to carry a relatively large tank of water, the operator must stop sweeping at frequent intervals to refill the tank. It may also be necessary to increase the size of the powered broom device to accommodate a relatively large water tank. Such dust suppression systems may be expensive and usually require periodic and substantial maintenance due to the added complexity and added components, such as pumps, motors, hoses, connections, etc. Furthermore, adding water to the loose material is undesirable because it leaves visible tracks and also creates mud-like mixtures of the loose particles. It is considerably more difficult to sweep mud-like mixtures of loose particles than to sweep the dry particles.
It is also common practice to slightly angle the rotational axis of the rotating bristle drum relative to the direction of movement in order to transfer the loose material slightly laterally, as the rotating bristles push the material forward. However, because the primary sweeping action is a forward pushing movement perpendicular to the rotational axis of the drum, and because the angle of the rotating drum of bristles is not a substantial angle, the loose particles move in a more forward direction than in a lateral direction. By continually moving the same loose particles in more of a forward direction than in a lateral direction, more dust and airborne clouds of particles result before the particles have been moved sufficiently to the side of the swept area. The circular rotational movement of the bristles and the slight angular displacement of the rotating drum requires that more sweeping action be applied before the loose particles are moved clear of the swept area. Furthermore, because of the slow lateral movement of the loose particles, the powered broom device might be operated at a slower forward advancement movement rate or the rotating rate of the bristle drum must be increased, to assure that enough sweeping energy is applied to clear the loose particles from the swept area.
In agricultural applications, side discharge rakes are used to create "windrows" of cut grass, plant stalks, grain crop stalks after harvesting, and the like. One type of side discharge rake has a plurality of bars which rotate in parallel in oval shaped paths and at an angle to the forward movement of the rake itself. The effect of the oval rotational path is to move the bars with a significant lateral movement component compared to the forward movement component of the rake. Each of the bars includes a number of spring teeth connected to it along its length. The spring teeth contact the previously-cut plant stalks and rake them to the side into the windrows. The spring teeth are resilient wire-like projections of approximately six to eight inches in length which extend from the parallel bars a sufficient distance to contact the cut plant stalks but not to contact stones or the soil. The spring tooth projections will also easily move through the upright bases of the plant stalks which remain in the soil after the stalks have been cut. After the windrows have been created by the action of the side discharge rake, another agricultural implement picks up the windrows of plant stalks. The plant stalks are thereafter formed into bales or are otherwise stored to be used for livestock feed.
Side discharge rakes are not suitable for sweeping. In fact, spring teeth of the side discharge rake are not intended to contact the soil, because contacting the soil might result in the introduction of stones and soils into the plant stalks, which would diminish the value as livestock feed and possibly create health problems for the livestock. The spring teeth are intended to efficiently avoid the bases of the plant stalks which remain in the soil. These considerations, and others, prevent and do not suggest the use of a side discharge rake in sweeping or broom applications.
It is with respect to this and other background information that the present invention has evolved.